Sometimes the value of a message is only temporary.  But nevertheless that temporar value can be enormous.  The latest essay by Dan Bricklin [http://www.bricklin.com/learningfromaccidents.htm Learning From Accidents and a Terrorist Attack] ponders on such cases:

 The work that is going on in the blogging world in regards to seeking out, 
 filtering, and disseminating information coming from a huge number of data
 sources for a diverse set of needs may be helpful for learning how to deal with
 such situations. Blogs, RSS, and the search engines are currently tuned for
 situations that unfold over many hours, days, or weeks. We need to look for
 principles that can be applied to minutes and seconds. The media forms of text,
 images, audio, and video are appropriate here, too.

Obviously the centralized system with a webcrawler wandering in the web and with the important messages waiting for it to index them will never be working in this scenario.  What is needed is a Push technology that would let the poster force everybody to listen just like we do in the physical world.  Of course any system with Push is susceptible for abuse with Spam, but we don't mute anyone so that they would not shout in the theatre offering their car to sale, we cope with such abuse with other methods.  I believe this is a place for a system based on the SocialRouting principles - with it each user needs to aggree on what is spam and what is not only with her neighbours, but still the network effect would let him to communicate globally.


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Related: 
* P2P search: http://slashdot.org/article.pl?sid=04/09/12/2240209&tid=95&tid=1
* the actual article: http://arxiv.org/abs/cond-mat/0406152  It is about how random walk after some threshhold length is guaranteed (approximately) to reach a highly connected node in a power law network.  Here it is used there for searching - a. e. pull technology, but the same argument should go for a push technology.
* PublishSubscribe